2a+4/a^3+8 a^4-b^4/a^3-b^3 a^4-b^4/a^4-b^4

Question

2a+4/a^3+8
a^4-b^4/a^3-b^3
a^4-b^4/a^4-b^4

Answer 1

(2а+4)/(а^3+8)=2(а+2)/(а+2)(а^2-2а+4)=
=2/(а^2-2а+4);

(а^4-в^4)/(а^3-в^3)=
=(а-в)(а+в)(а^2+в^2)/(а-в)(а^2+ав+в^2)=
=(а+в)(а^2+в^2)/(а^2+ав+в^2).